Recirculating Muffler Apparatus and Method

ABSTRACT

A recirculating flow muffler apparatus and method includes a case with an exterior surrounding an interior space, the interior space forming a return area, where the case has a front and a rear. An inlet is provided at the front of the case, the inlet extending into the case interior space. A mixing tube is provided within the interior space, where the return area surrounds the mixing tube. The mixing tube has a first end and a second end where the first end is bigger than the inlet and the first end is located next to the inlet. An outlet is provided at the rear of the case, the outlet extending out of the interior space of the case and the second end of the mixing tube includes an opening between it and the outlet.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of previously filed U.S. provisional patent application No. 61/836,881 filed Jun. 19, 2013 and PCT application PCT/US2014/42877 filed 18 Jun. 2014 for a “Recirculating Flow Muffler Apparatus and Method”, The Applicant hereby claims the benefit of these applications under 35 U.S.C. §119. The entire content of these applications are incorporated herein by this reference.

FIELD OF THE INVENTION

This invention relates to a recirculating flow muffler apparatus and method. In particular, in accordance with one embodiment, the invention relates to a recirculating flow muffler apparatus consisting of a case with an exterior surrounding an interior space, the interior space forming a return area, where the case has a front and a rear. An inlet is provided at the front of the case, the inlet extending into the case interior space. A mixing tube is provided within the interior space, where the return area surrounds the mixing tube. The mixing tube has a first end and a second end where the first end is bigger than the inlet and the first end is located next to the inlet. An outlet is provided at the rear of the case, the outlet extending out of the interior space of the case and the second end of the mixing tube includes an opening between it and the outlet.

BACKGROUND OF THE INVENTION

A problem exists with regard to the noise associated with exhaust from internal combustion engines. Mufflers currently on the market restrict and or disrupt the exhaust gas flow and/or do not control noise very well. Restriction and disruption of gas flow decreases the efficiency of the engine, forcing it to work harder in effect. On the other hand, current state of the art mufflers that have less restrictions and disruptions are more efficient but provide only minimal noise reduction.

Thus, there is a need in the art for a muffler that has only minimum restrictions and disruptions while at the same time has much better noise control.

It therefore is an object of this invention to provide a muffler that provides maximum noise reduction with minimum restriction to flow thereby increasing engine efficiency and fuel economy and reducing emissions. It is a further object to provide a muffler that is adaptable to multiple engine and vehicle configurations and is easy to install and remove.

SUMMARY OF THE INVENTION

Accordingly, the recirculating flow muffler apparatus of the present invention, according to one embodiment, includes a case with an exterior surrounding an interior space, the interior space forming a return area, where the case has a front and a rear. An inlet is provided at the front of the case, the inlet extending into the case interior space. A mixing tube is provided within the interior space, where the return area surrounds the mixing tube. The mixing tube has a first end and a second end where the first end is bigger than the inlet and the first end is located next to the inlet. An outlet is provided at the rear of the case, the outlet extending out of the interior space of the case and the second end of the mixing tube includes an opening between it and the outlet.

All terms used herein are given their normal meaning within the art. Thus, “case” describes a structure with an outside and an inside. The “case” of the present invention may be in any form desired or useful for the circumstances such as, for example only and not by way of limitation, a rectangular form, including an equal sided square or one with two longer sides and two shorter sides or even one with sides of non-uniform length. Additionally, the case may include bends and angles and the body may be round or oval or block shaped, for example only and not by way of limitation.

Further, “inlet” and “outlet” describe structures that provide ingress and egress to the inside of the case of the invention. They may be any useful form, such as for example only a cylindrically shaped pipe form as is most commonly found in exhaust systems. Likewise, the “mixing tube” describes a tube, of any desired form, into which exhaust is directed by the inlet. The “mixing” element refers to the fact that exhaust and recirculated exhaust enter the first end of the mixing tube and are mixed together as will be more fully described hereafter, and

According to one aspect of the invention, the inlet is tapered and extends into the first end of the mixing tube. In another aspect, the first end of the mixing tube is flared.

In one aspect, the mixing tube is suspended within the interior space by one or more connectors where the connectors connect the mixing tube to the case within the interior space. In another aspect, the connectors only partially block the interior space. In a further aspect, the connectors block the interior space and the connectors include at least one hole providing an opening from one side of the connector to the other side of the connector in the interior space. In yet another aspect, the connectors are located at the first end and at the second end of the mixing tube.

In one aspect, the case includes more than one outlet or more than one inlet or any combination of inlets and outlets. In a further aspect, the length of the mixing tube between the first end and the second end is angled from between zero to three hundred sixty degrees.

According to another embodiment of the invention, a recirculating flow muffler apparatus includes a case with an exterior surrounding an interior space, the interior space forming a return area, where the case has a front and a rear. An inlet is provided at the front of the case, the inlet extending into the case interior space and the inlet including a tapered end. A mixing tube is provided within the interior space, where the return area surrounds the mixing tube, the mixing tube having a first end and a second end where the first end is bigger than the inlet and where the tapered end of the inlet is even with or extends at least partially into the first end of the mixing tube. Connectors connecting the mixing tube to the case within the interior space are provided such that the mixing tube is suspended within the interior space and surrounded by the return area. And, an outlet at the rear of the case is provided, the outlet extending out of the interior space of the case, and where the second end of the mixing tube includes an opening between it and the outlet.

In one aspect of this invention, the first end of the mixing tube is flared. In another aspect, the connectors only partially block the interior space. In a further aspect, the connectors block the interior space and the connectors include at least one hole providing an opening from one side of the connector to the other side of the connector in the interior space. In another aspect, the connectors are located at the first end and at the second end of the mixing tube.

In another aspect, the case includes more than one outlet or more than one inlet or any combination of inlets and outlets. In a further aspect, the length of the mixing tube between the first end and the second end is angled from between zero to three hundred sixty degrees.

In a further aspect, the mixing tube includes an inside that is a smooth surface. As used herein, the term “smooth surface” describes a surface that includes no interruptions, valleys or hills or projections or obstructions along its length and is uniformly smooth along that length as is the case for the inside of a typical pipe or tube, for example.

According to another embodiment a recirculating flow muffler method consists of:

a. providing a case with an exterior surrounding an interior space, the interior space forming a return area, where the case has a front and a rear; an inlet at the front of the case, the inlet extending into the case interior space; a mixing tube within the interior space, where the return area surrounds the mixing tube, the mixing tube having a first end and a second end where the first end is bigger than the inlet and the first end is located next to the inlet; and an outlet at the rear of the case, the outlet extending out of the interior space of the case, and where the second end of the mixing tube includes an opening between it and the outlet; and

b. connecting the inlet with an engine exhaust such that exhaust passes through the inlet into the mixing tube and out of the outlet while at least some of the exhaust passes into the return area at the second end of the mixing tube and recirculates to the inlet where it again enters the first end of the mixing tube.

In one aspect, the inlet is tapered and extends into the first end of the mixing tube. In another aspect, the mixing tube is suspended within the interior space by one or more connectors where the connectors connect the mixing tube to the case within the interior space.

DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and the accompanying drawings in which:

FIG. 1 is a top view of the recirculating flow muffler of the present invention;

FIG. 2 is a perspective view of the invention of FIG. 1 with two outlets and a pair of connectors with flow through holes;

FIG. 3 is a top view of the invention of FIG. 1 illustrating another manner of creating an opening between the second end of the mixing tube and the outlet;

FIG. 4 is a top view of the invention of FIG. 1 with two outlets and two inlets;

FIG. 5 is a top view of the invention of FIG. 1 with a case bent in a ninety degree angle and a mixing tube bent in ninety degrees along its length between the first end and the second end of the mixing tube; and

FIG. 6 is a top view of the invention of FIG. 1 with the case in a rectangular form and the mixing tube bent three hundred and sixty degrees along its length between the first end and the second end of the mixing tube.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiment of the present invention is illustrated by way of example in FIGS. 1-6. With specific reference to FIGS. 1 and 2, recirculating flow muffler 10 includes a case 12 with an exterior 14 surrounding an interior 16 forming a return area 18 on the inside of the case 12 as will be more fully described hereafter. Case 12 has a front 20 and a rear 22.

An inlet 24 is provided at the front 20 of case 12. Met 24 starts on the outside of case 12 and extends some distance into the interior 16 of case 12 as shown. Preferably, inlet 24 includes a tapered end 26 on the end of the inlet 24 on the inside 16 of case 12, also as shown and as will be described more fully hereafter. It should be understood that the tapered end 26 may be included or not.

Mixing tube 28 is located in the interior 16 of case 12 and is at least partially if not completely surrounded by return area 18 as shown. Mixing tube 28 has a first end 30 and a second end 32. In one embodiment, first end 30 includes a flare 34 thus making the first end 30 bigger, i.e. larger and more open, than the tapered end 26 of inlet 24, all as illustrated in the figure. First end 30 is located next to inlet 24 as shown and, preferably inlet 24 is even with or actually located at least partially within first end 30 of mixing tube 28. Again, inlet 24 may include tapered end 26 that is located within the first end 30 of mixing tube 28 but which is otherwise not connected with mixing tube 28.

Outlet 36 is provided at the rear 22 of case 12. Outlet 36 extends out of the interior 16 and preferably at least partially beyond the rear 22. Outlet 36 may form the tail pipes of a typical exhaust system on a car, for example only and not by way of limitation, or the stubs upon which custom exhausts are attached. Outlet 36 may extend somewhat into the interior 16 of case 12 as shown in FIG. 1 or not at all as shown in FIGS. 2, 4, 5 and 6 as desired and found useful.

Importantly, the “connection” between the second end 32 of mixing tube 28 and outlet 36 includes an opening 38. FIG. 1 illustrates the formation of the opening 38 by the lack of a direct connection between the second end 32 and outlet 36. Here the second end 32 is next to and somewhat overlaps the outlet 36 but opening 38 allows exhaust to escape through the opening 38. The flow of exhaust is demonstrated by arrows showing the exhaust entering recirculating flow muffler at inlet 24 being directed into mixing tube 28 and most of it passing out of outlet 36. However, some of the exhaust and associated noise etc. escapes into the return area 18 at the second end 32 of mixing tube 28. From there the exhaust in the return area 18 is drawn back to the first end 30 of the mixing tube 28. It is drawn back because a venturi effect is created by the combination of the inlet 24 in close proximity to the first end 30 particularly when the inlet includes tapered end 26 and/or first end 30 includes flare 34. By experimentation and testing, Applicant has found that this combination of structures greatly reduces the volume of noise/sound leaving outlet 36.

It should be noted that the inside of mixing tube 28 is smooth. That is there are no obstructions, hills, valleys or any projections or obstacles. It is a plain, uniform surface all as illustrated. Applicant has determined that this reduces turbulence and back pressure and enhances the efficiency of any motor (not shown) to which the inlet 24 is connected.

Still referring to FIGS. 1 and 2, connectors 40 are shown. Connectors 40 connect mixing tube 28 to the inside of case 12 and support and suspend it, preferably, within case 12 such that return area 18 surrounds mixing tube 28 as shown. Connectors 40 may be simple tabs secured by welding, glue or some equivalent and connectors 40, may therefore only partially and minimally obstruct the flow of exhaust as described above and illustrated. Preferably, as shown, connectors 40 are positioned so as to best prevent movement of mixing tube 28 within interior 16 as, for example only, at the first end 30 and the second end 32. Other useful positions may be adopted as well as more or fewer connectors 40.

Referring now specifically to FIG. 2, connectors 40 are shown in which connectors 40 totally obstruct the flow of exhaust within the return area 18. In this embodiment, connectors 40 include one or more holes 42. Exhaust that does not pass directly out of outlet 36 and which escapes is forced to travel through holes 42 as it is sucked back to the first end 30 of mixing tube 28 by the venturi effect of inlet 24 as described above. This structure, Applicant has determined by testing, has the unexpected benefit of reducing sound output even further than without it. Further, Applicant has found that holes 42 of different diameters also enhances sound reduction and enables the recirculating flow muffler 10 of the present invention to be “tuned” and adapted to various situations in order to achieve the best sound reduction with the least restriction of flow.

FIG. 2 also illustrates two outlets 36 are enabled by the invention and that one or more outlet 36 is included within the scope of the present invention.

Referring now to FIG. 3, another embodiment of the invention is illustrated. Here, for example, it is shown that second end 32 of mixing tube 28 may be connected to outlet 36 such that mixing tube 32 and outlet 28 are one integral piece, for example only. However, importantly, openings 38 are provided at, or after, second end 32 such that exhaust is allowed to escape into return area 18. Thus, in this configuration, the recirculating flow muffler 10 functions as described above in that much of the exhaust passes directly out of the outlets 36 while a portion of the exhaust recirclulates through first end 30.

FIG. 3 also illustrates a rectangular shaped case 12 and a connector 40 that forms a box around mixing tube 28, In this form, connector 40 may also include holes 42 that allow recirculating exhaust to flow in and around it back to first end 30 as shown by the arrows in the figure, thereby contributing to sound nullification.

FIG. 3 also illustrates that, when and where deemed necessary, supports 44 may be provided to stabilize inlet 24, or any other element of the device.

Referring to FIG. 4, recirculating flow muffler apparatus 10 is shown with two inlets 24, in combination with two mixing tubes 28 and two outlets 36 all arranged as described above. It should be noted, again, that the scope of the invention includes one or more inlets, mixing tubes and outlets in various combinations without departing from the invention as set forth herein. Thus there may be more inlets 24 than outlets 36 , more outlets 36 than inlets 24 and one or more mixing tubes 28.

Referring now to FIG. 5, an important feature of the invention is illustrated in which the length of the mixing tube 28 between the first end 30 and the second end 32 is angled, in this illustration, to ninety degrees. That is, the mixing tube 28 is bent in the middle at ninety degrees. Case 12, in this structure, is also bent or angled at ninety degrees. All the elements of the invention as set forth and described above are present and functional. This illustrates that the recirculating flow muffler 10 functions as described above even when in non-linear alignment. Thus, the recirculating flow muffler 10 may be formed to fit in any situation.

FIG. 5 also illustrates the structure in which outlet 36 does not actually extend into the interior 16 of the case 12 but is simply an opening through which exhaust may pass from the second end 32 of mixing tube 28 and the interior 16 of case 12.

Referring now to FIG. 6, it is shown that mixing tube 28 may be bent, curved, angled up to three hundred and sixty degrees, a complete circle, if space limitations or the situation requires. Here exhaust enters inlet 24 and is directed into the first end 30 of mixing tube 28, then travels in a compete circle until it exits the second end 32. In this instance the outside case 12, however, is a simple rectangular form.

In summary, Applicant's recirculating flow muffler 10 has been found to have minimum disruption and restriction of exhaust gas flow with much better noise, resonance control than any prior art devices. In fact, by testing, Applicant has found that this structure is a simple, efficient design that causes almost no restriction to gas flow which allows internal combustion engines, for example only, to be more efficient. This in turn results in an increase in power, improved fuel economy and lower harmful emissions. These benefits dictate that the invention will find widespread use in the aftermarket replacement industry where individuals will modify existing vehicles for improved performance and economy. Further, because the invention is capable of being produced in many equally efficient configurations, it is suitable to be installed on new vehicles as well.

By way of further explanation, the Applicant's recirculating flow muffler creates a much to be desired muffler with a near zero resistance to exhaust flow while giving enhanced sound control without having resonance or drone at any cruising speed. The structure enables this by keeping the mixing tube smooth and, preferably, the same diameter or larger than the exhaust pipes, outlet, of the vehicle. Sound control is achieved by having some of the exhaust gases and sound waves recirculate and travel, Applicant has determined, seven times further or more than the sound waves and exhaust in the mixing tube that pass directly out of the outlet. Holes in the connectors also ensure that the sound waves travel various distances and in the process, cancel some of them.

The inlet and outlet may be the same diameter. The first end 30 of the mixing tube 28, however, is bigger, such as twenty-five to fifty percent bigger, than the inlet 24. The velocity of the exhaust gases entering the first end 30 of mixing tube 28 from the inlet 24, particularly inlet 24 with tapered end 26, creates a vacuum in the gap between the smaller inlet 24 and the larger first end 30. The vacuum draws gases and sound waves from the return area 18 and from the second end 32 and recirculates it to the first end 30 where it enters mixing tube 28 and is mixed with exhaust therein. Some exhaust, again, has escaped from the second end 32 of mixing tube 28 through openings 38 before passing from outlet 36.

The muffler of the present invention may be round, oval or any desired shape and in various lengths. Larger and longer bodies have been found to provide best sound control.

The description of the present embodiments of the invention has been presented for purposes of illustration, but is not intended to be exhaustive or to limit the invention to the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. As such, while the present invention has been disclosed in connection with an embodiment thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention as defined by the following claims. 

What is claimed is:
 1. A recirculating flow muffler apparatus comprising: a. a case with an exterior surrounding an interior space, said interior space forming a return area, wherein the case has a front and a rear; b. an inlet at the front of the case, said inlet extending into said case interior space; c. a mixing tube within said interior space, wherein said return area surrounds said mixing tube, said mixing tube having a first end and a second end wherein said first end is bigger than said inlet and said first end is located next to said inlet; and d. an outlet at the rear of the case, said outlet extending out of said interior space of said case, and wherein said second end of said mixing tube includes an opening between it and said outlet.
 2. The apparatus of claim 1 wherein said inlet is tapered and extends into said first end of said mixing tube.
 3. The apparatus of claim 1 wherein said first end of said mixing tube is flared.
 4. The apparatus of claim 1 wherein said mixing tube is suspended within the interior space by one or more connectors wherein said connectors connect the mixing tube to the case within the interior space.
 5. The apparatus of claim 4 wherein said connectors only partially block said interior space.
 6. The apparatus of claim 4 wherein said connectors block said interior space and wherein said connectors include at least one hole providing an opening from one side of the connector to the other side of the connector in said interior space.
 7. The apparatus of claim 4 wherein said connectors are located at said first end and at said second end of said mixing tube.
 8. The apparatus of claim 1 wherein said case includes a combination of inlets, outlets and mixing tubes selected from a group consisting of: one or more than one inlet, one or more than one outlet and one or more than one mixing tube.
 9. The apparatus of claim 1 wherein the length of said mixing tube between said first end and said second end is angled from between zero to three hundred sixty degrees.
 10. A recirculating flow muffler apparatus comprising: a. a case with an exterior surrounding an interior space, said interior space forming a return area, wherein the case has a front and a rear; b. an inlet at the front of the case, said inlet extending into said case interior space and said inlet including a tapered end; c. a mixing tube within said interior space, wherein said return area surrounds said mixing tube, said mixing tube having a first end and a second end wherein said first end is bigger than said inlet and wherein said tapered end of said inlet is even with or extends at least partially into said first end of said mixing tube; d. connectors connecting the mixing tube to the case within the interior space such that said mixing tube is suspended within the interior space and surrounded by said return area; and e. an outlet at the rear of the case, said outlet extending out of said interior space of said case, and wherein said second end of said mixing tube includes an opening between it and said outlet.
 11. The apparatus of claim 10 wherein said first end of said mixing tube is flared.
 12. The apparatus of claim 10 wherein said connectors only partially block said interior space.
 13. The apparatus of claim 10 wherein said connectors block said interior space and wherein said connectors include at least one hole providing an opening from one side of the connector to the other side of the connector in said interior space.
 14. The apparatus of claim 10 wherein said connectors are located at said first end and at said second end of said mixing tube.
 15. The apparatus of claim 10 wherein said case includes a combination of inlets, outlets and mixing tubes selected from a group consisting of: one or more than one inlet, one or more than one outlet and one or more than one mixing tube.
 16. The apparatus of claim 10 wherein the length of said mixing tube between said first end and said second end is angled from between zero to three hundred sixty degrees.
 17. The apparatus of claim 10 wherein said mixing tube includes an inside that is a smooth surface.
 18. A recirculating flow muffler method comprising: a. providing a case with an exterior surrounding an interior space, said interior space forming a return area, wherein the case has a front and a rear; an inlet at the front of the case, said inlet extending into said case interior space; a mixing tube within said interior space, wherein said return area surrounds said mixing tube, said mixing tube having a first end and a second end wherein said first end is bigger than said inlet and said first end is located next to said inlet; and an outlet at the rear of the case, said outlet extending out of said interior space of said case, and wherein said second end of said mixing tube includes an opening between it and said outlet; and b. connecting the inlet with an engine exhaust such that exhaust passes through the inlet into the mixing tube and out of the outlet while at least some of the exhaust passes into the return area at the second end of the mixing tube and recirculates to the inlet where it again enters the first end of the mixing tube.
 19. The method of claim 18 wherein said inlet is tapered and extends into said first end of said mixing tube.
 20. The method of claim 18 wherein said mixing tube is suspended within the interior space by one or more connectors wherein said connectors connect the mixing tube to the case within the interior space. 